Illumination assembly including thermal energy management

ABSTRACT

An illumination assembly includes a polymeric substrate, an electrical circuit including two conductors supported by the polymeric substrate, an LED electrically coupled to the two conductors, and a heat spreader thermally coupled to the LED. The two conductors can be printed on the polymeric substrate, embedded within the polymeric substrate, or lie atop the polymeric substrate. The illumination assembly may be fabricated in three-dimensional form factors.

This invention was made with government support under Contract No.DE-SC0011865 awarded by the U.S. Department of Energy. The governmenthas certain rights in the invention.

BACKGROUND OF THE INVENTION

The present invention relates to illumination assemblies, and moreparticularly to illumination assemblies that provide thermal energymanagement.

Solid-state lighting, such as those utilizing light emitting diodes(LEDs), has been adopted for widespread applications. However,solid-state lighting design involves a balance of thermal, mechanical,optical, and electrical considerations. In particular, thermalconsiderations dictate the practical limits of many designs.

In solid-state lighting, electronics are assembled on a printed circuitboard, which allows component design only in two dimensions. Thislimitation is generally acceptable where there is a high demand fordensely populated components and low demand for populating thosecomponents throughout a three-dimensional form factor. In contrast, inLED applications, the demand for high component density is lower, butthe need to accommodate complex and three-dimensional form factors ishigher.

Unfortunately, existing technologies do not permit three-dimensionalform factors in desired balances with other considerations.

SUMMARY OF THE INVENTION

The aforementioned problems are overcome in the present invention inwhich an illumination assembly includes a polymeric substrate and a heatspreader supported by the substrate to provide electrical current andthermal energy management to solid-state lighting applications usingLEDs.

According to one embodiment, an illumination assembly includes a firstpolymeric substrate, an electrical circuit including two conductorssupported by the first polymeric substrate, an LED electrically coupledto the two conductors, and a heat spreader supported by the substrateand thermally coupled to the LED.

In another embodiment, an illumination assembly includes a firstpolymeric substrate, an electrical circuit including a first pair ofconductors embedded within the first polymeric substrate and a secondpair of conductors printed on the first polymeric substrate, an LEDelectrically coupled to the second pair of conductors, and a heatspreader supported by the substrate and thermally coupled to the LED.

In yet another embodiment, a method of forming an illumination assemblycomprises: (1) forming a polymeric substrate having opposing first andsecond sides, (2) forming an electrical circuit including two conductorssupported on the first side of the polymeric substrate, (3) electricallycoupling an LED with the two conductors, (4) thermally coupling a heatspreader with the LED, the heat spreader at least primarily disposed onthe second side of the polymeric substrate, and (5) over-molding a firstpolymeric layer over at least portions of the LED, the two conductors,and the polymeric substrate.

These and other advantages and features of the invention will be morefully understood and appreciated by reference to the description of thecurrent embodiments and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cross-section of an illuminationassembly according to a first embodiment of the invention.

FIG. 2 is a schematic cross-sectional view of a portion of theillumination assembly of FIG. 1 according one embodiment of theinvention.

FIG. 3 is a schematic cross-sectional view of a portion of theillumination assembly of FIG. 1 according one embodiment of theinvention.

FIG. 4 illustrates a process for forming an illumination assemblyaccording to another embodiment the invention.

FIG. 5 is a perspective view of an illumination assembly according toanother embodiment of the invention.

FIG. 6 is a cross-sectional view of a portion of an illuminationassembly according to another embodiment of the invention.

FIG. 7 is a cross-sectional view of a portion of an illuminationassembly according to another embodiment of the invention.

FIG. 8 is a cross-sectional view of a portion of an illuminationassembly according to another embodiment of the invention.

FIG. 9 is a cross-sectional view of a portion of an illuminationassembly according to another embodiment of the invention.

FIG. 10 is a cross-sectional view of a portion of an illuminationassembly according to another embodiment of the invention.

FIG. 11 is a cross-sectional view of a portion of an illuminationassembly according to another embodiment of the invention.

DESCRIPTION OF THE CURRENT EMBODIMENTS I. Structure

With reference to FIG. 1, an illumination assembly 10 is illustrated inaccordance with a first embodiment of the invention. The illuminationassembly 10 can include an electrical circuit 11 comprising a pluralityof circuit traces which include at least two conductors 12 a-b forproviding electrical current to connected components and at least oneheat spreader 14 for dissipating thermal energy (i.e. heat) generated byan electrical component. The conductors 12 a-b can be supported by apolymeric substrate 16 made of a first polymeric material. In thepresent example in which the conductors 12 a-b are at least partiallyembedded within the polymeric substrate 16, the conductors 12 a-b canalso be referred to as embedded conductors. The electrical circuit 11can also include a plurality of circuit traces which include printedconductors 18 a-d (see also FIG. 2) which are also supported by thepolymeric substrate 16 by printing the conductors 18 a-d on an interiorsurface 20 of the polymeric substrate 16. The illumination assembly 10can also include a light source 22, such as a light emitting diode(LED), and additional electrical components 24-26, non-limiting examplesof which include a resister, diode, capacitor, conductor, another LED,or any other suitable electrical components.

At least a portion of the printed conductors 18 a-d, LED 22, andelectrical components 24-26 can be covered by and/or embedded within afirst polymeric layer 28 made of a second polymeric material. In thismanner, the polymeric substrate 16 can form a first housing portion andthe first polymeric layer 28 can form a second housing portion, with thefirst and second housing portions 16 and 28 encompassing the elements ofthe electrical circuit 11. The first polymeric layer 28 can include alens portion 30 adjacent the LED 22 for directing light emitted by theLED 22. The polymeric substrate 16 and/or the first polymeric layer 28can be formed to include additional structures, non-limiting examples ofwhich include a connector portion 32, a light blocking feature 34, andattachment apertures 36. The polymeric substrate 16 and the firstpolymeric layer 28 can be made from the same or different material. Boththe polymeric substrate 16 and the first polymeric layer 28 can be madefrom an electrically insulating material that can optionally bethermally conductive. Non-limiting examples of materials suitable forthe polymeric substrate 16 and/or the first polymeric layer 28 includeacrylics, polycarbonates, silicones, polyethylene terephthalate,acrylonitrile butadiene styrene (ABS), polybutylene terephthalate (PBT)based materials, and combinations thereof. The polymeric substrate 16and the first polymeric layer 28 can be made from the same or differentmaterials. In one example, the first polymeric layer 28 can be made of atransparent moldable material, non-limiting examples of which includeacrylics, polycarbonates, silicones, and ABS based materials.

In the embodiment of FIG. 1, the electrical circuit 11 includes at leastone pair of embedded conductors 12 a-b that are at least partiallyembedded within the polymeric substrate 16 as well as printed conductors18 that are printed onto the interior surface 20 of the polymericsubstrate 16. In one example, the embedded conductors 12 a-b can be madefrom a single sheet of metal that is cut to isolate various componentsof the circuit 11 as desired or each trace of the electrical circuit 11can be independently formed and electrically coupled or isolated asdesired depending on the design of the circuit. The embedded conductors12 a-b can be made from metals such as plated steel, brass, copper, orother materials known in the art.

One or more of the printed conductors 18 a-d can be electrically coupledwith the electrical circuit 11 through at least one pair of embeddedconductors (such as illustrated in FIG. 5) for receiving electricalcurrent from a suitable current source (not shown) coupled with theelectrical circuit 11 through the connector portion 32. The printedconductors 18 a-d can be printed using conductive inks, non-limitingexamples of which include inks containing graphine or metallicnanoparticles, such as copper nanoparticle-based inks. Examples ofcommercially available inks include DuPont 5025, PE825, and 5043, all ofwhich are a silver composite conductor ink available from DuPont®, andthe Electrodag™ family of conductive inks available from Henkel. Theprinted conductors 18 a-d can be directly printed onto exposed terminalsof embedded conductors of the electrical circuit 11 to electricallycouple the printed conductors 18 a-d to the conductors. Alternatively,the printed conductors 18 a-b can be coupled to the embedded conductorsof the electrical circuit 11 by a solder joint or a conductive epoxyjoint. The printed conductors 18 a-d can be printed and cured using anysuitable technique, non-limiting examples of which include silk screen,stencil, laser sinter, laser etch, chemical etch, and additive printing.

Referring now to FIG. 2, the LED 22 can be electrically coupled with theprinted conductors 18 c-d for receiving electrical current and thermallycoupled with the heat spreader 14 for dissipating heat generated by theLED 22. As shown schematically in FIG. 2, the printed conductors 18 c-deach include terminals 50 and 52 to which the LED 22 can be electricallycoupled to allow current to flow through the LED 22. The LED 22 includesconnectors 54 and 56 which can be electrically coupled to the adjacentterminals 50 and 52, respectively. The LED connectors 54 and 56 can bein the form of leads that can be coupled with the adjacent terminals 50and 52 through soldering. Alternatively, the LED 22 can be coupled withthe terminals 50 and 52 using a conductive epoxy, such as an epoxy dopedwith silver fragments or particles and/or other conductive metals. Anexample of a suitable material includes a heat-bondable, electricallyconductive adhesive film, such as Anisotropic Conductive Film 7376-10,available from 3M™.

The LED 22 can span a gap 58 between the printed conductors 18 c and 18d. The heat spreader 14 can be thermally coupled with the LED 22 in thegap 58 for dissipating heat generated by the LED 22. The LED 22 caninclude a heat conducting component 59, such as a metal plate, joinedwith or at least partially embedded within the body of the LED 22component. As illustrated in FIG. 2, the heat spreader 14 can include anexposed portion 60 that extends beyond the interior surface 20 of thepolymeric substrate 16 for direct contact with the metal plate 59 of theLED 22 and an unexposed portion 62 that does not extend beyond theinterior surface 20. The heat spreader 14 can be configured such that amajority of the heat spreader 14 does not extend beyond the interiorsurface 20 and thus the heat spreader 14 can be considered as beingpredominately disposed exteriorly of the interior surface 20. Theunexposed portion 62 can be completely embedded within the polymericsubstrate 16 (as shown) or, alternatively, the unexposed portion 62 canextend beyond an exterior surface 64 of the polymeric substrate 16. Anadditive, such as solder, a thermally conductive epoxy, grease, or othercoating can optionally be provided between the exposed portion 60 of theheat spreader 14 and the metal plate 59 to facilitate securing the LED22 in place and/or to facilitate thermal contact between the LED 22 andthe heat spreader 14.

While the heat spreader 14 is illustrated as having a generallyarched-shaped cross-section, it will be understood that the heatspreader 14 can have a variety of different cross-sectional shapesdepending on the design of the illumination assembly. For example, theheat spreader 14 can be a material having a non-uniform thickness ratherthan the arched-shape cross-sectional shape illustrated in FIG. 2.

With reference to FIG. 3, in another example, the heat spreader 14 doesnot include a portion that extends beyond the interior surface 20 andthus the heat spreader 14 can be considered as being entirely disposedexteriorly of the interior surface 20. In this example, the heatspreader 14 is not in direct contact with the LED 22, but can bethermally coupled to the LED 22 through the polymeric substrate 16,which can be made from a thermally conductive and electricallyinsulating material. Heat generated by the LED 22 transferred to theconductors 18 c-d can also be dissipated by the heat spreader 14 throughthe polymeric substrate 16. The metal plate 59 of the LED 22 can beconfigured to be in thermal contact with the polymeric substrate 16 tofacilitate heat transfer from the LED 22 to the heat spreader 14. Whilethe heat spreader 14 is illustrated as being embedded within thepolymeric substrate 16, the heat spreader 14 can also include a portionthat extends beyond the exterior surface 64 of the polymeric substrate16 to increase the surface area of the heat spreader 14 and increase theamount of heat dissipated.

Referring again to FIG. 1, the additional electrical components 24-26can be electrically coupled with the printed conductors 18 a-b (e.g.electrical component 24) or with the embedded conductors 12 a-b (e.g.electrical component 26). The embedded conductors 12 a-b and the heatspreader 14 can include exposed portions on the interior surface 20 ofthe polymeric substrate 16 for coupling with an electrical component, asillustrated in FIGS. 1-2. Alternatively, the embedded conductors 12 a-band/or heat spreader 14 can be completely encapsulated within thepolymeric substrate 16 and an additional component coupled with theembedded conductors 12 a-b and/or heat spreader 14 can project from theinterior surface 20 of the polymeric substrate 16 for coupling theelectrical component with the embedded conductors 12 a-b and/or heatspreader 14.

The polymeric substrate 16 and first polymeric layer 28 can be the sameor different and are preferably made from a non-conducting polymericmaterial that can be molded around the components of the illuminationassembly 10. The polymeric substrate 16 and first polymeric layer 28 canbe molded around the components of the illumination assembly 10according to any known method, examples of which are disclosed in U.S.Pat. No. 7,909,482 to Veenstra et al., entitled “Electrical DeviceHaving Boardless Electrical Component Mounting Arrangement,” issued Mar.22, 2011, which is incorporated herein by reference in its entirety.

FIG. 4 illustrates an exemplary method 100 for forming the illuminationassembly 10 according to a two-shot molding process similar to thatwhich is disclosed in U.S. Pat. No. 7,909,482 to Veenstra et al. Themethod 100 can begin at 102 with forming a metal web that includes atleast two conductive circuit elements which will form the basis for theembedded conductors 12 a-b. The at least two conductive circuit elementscan be made from cutting, bending, and/or stamping a metal sheet to formthe metal web having the desired conductors 12 a-b.

At 104 any LEDs or other electrical components that are to beelectrically coupled directly with the embedded conductors 12 a-b, suchas electrical component 26, are coupled with the appropriate conductorsusing soldering or any other suitable method. At 106 the heat spreader14 can be positioned adjacent the metal web in a position correspondingto where the LED 22 will be located. The heat spreader 14 can be athermally conductive component that can be made from the same materialas the metal web at 102 or a different material. In an exemplaryembodiment, the heat spreader 14 is a portion of the metal web that iselectrically isolated from current flow through the web.

The thus assembled web, electrical components, and heat spreader 14 forma circuit pre-form that can be placed within a cavity of a tooling moldhaving a shape corresponding to the first housing portion that is formedby the polymeric substrate 16 at 108. While the heat spreader 14 isdescribed as being placed in the mold cavity at the same time as theassembled web, it is also within the scope of the invention for the heatspreader 14 to be a separate element that is placed in the mold cavitybefore or after the assembled web.

The first polymeric material is provided in molten form to the moldcavity at 110 in a first molding shot to form the polymeric substrate 16in which the web, electrical components, and heat spreader 14 are atleast partially embedded. The mold can be configured to leave at least aportion of the heat spreader 14 exposed on the interior surface 20 ofthe polymeric substrate 16, as illustrated in FIG. 2, or the mold can befigured such that no portion of the heat spreader 14 extends beyond theinterior surface 20, as illustrated in FIG. 3. Additional portions ofthe web can also be left exposed as needed for coupling additionalelectrical components with the web after the first molding shot.

At 112, the printed conductors 18 a-d can be printed onto the interiorsurface 20 of the polymeric substrate 16 adjacent the heat spreader 14.In one example, the conductors 18 a-d can be printed using a printerwith a print head with X-Y motion control relative to the polymericsubstrate 16 according to an additive screen printing process. The LED22 can be electrically coupled to the printed conductors 18 c-d andthermally coupled with the heat spreader 14 in the manner describedabove in FIGS. 2 and 3. Additional electrical components 24 can beelectrically coupled with the printed conductors 18 a-b as desired toform the completed electrical circuit.

At 114, the completed electrical circuit can be placed within a secondmold cavity having a shape corresponding to the second housing portionthat is formed by the first polymeric layer 28. The second polymericmaterial can be provided in molten form to at least partiallyembed/cover the LED 22, electrical components 24, 26, and printedconductors 18 a-d within the first polymeric layers 28 in a secondmolding shot. The second polymeric material can be the same or differentthan the first polymeric material in the first molding shot at 110. Inone example, the second polymeric material can be a material that allowsat least a portion of the light emitted from the LED 22 to travelthrough the second polymeric material to an exterior of the illuminationassembly 10 for providing illumination. The second polymeric materialcan be transparent, translucent and/or colored to provide the emittedlight with the desired characteristics.

Alternatively, the method 100 can include an optional additional step116 for forming the lens portion 30 above the LED 22. In one example,the lens portion 30 can be formed in a third molding shot using a thirdpolymeric material that is different from the second polymeric materialto provide the desired light emitting characteristics. Additionally, oralternatively, the formation of the lens portion 30 can include treatingthe polymeric material molded over the LED 22 to provide the desiredlight emitting characteristics. For example, the polymeric materialmolded over the LED 22 can include a three-dimensional shape and/ortexture configured to control the distribution of light emitted throughthe lens portion 30. In one example, the lens portion 30 can be madefrom any suitable transparent material, non-limiting examples of whichinclude acrylics, polycarbonates, silicones, and ABS based materials.

In another example, the second molding shot at 114 may include leavingan opening in the first polymeric layer 28 in the area above the LED 22to allow at least a portion of the light emitted by the LED 22 to escapefrom the lighting assembly 10 unimpeded by the first polymeric layer 28.In this example, the lighting assembly 10 can be coupled with a device,such as a vehicle tail light, which includes a component that canoperate as a lens for the light emitted by the LED 22.

While each of the polymeric substrate 16 and the first polymeric layer28 are described as being formed in a single shot, it is within thescope of the invention that one or more shots may be used to form thepolymeric substrate 16 and/or the first polymeric layer 28.

Each of the steps of the method 100 can be modified depending on themanner in which the electrical circuit 11, electrical components 22-26,and heat spreader 14 are configured. For example, in a configuration inwhich the heat spreader 14 is embedded within the first polymeric layer28, rather than the polymeric substrate 16, such as in the embodiment ofFIG. 6, the heat spreader 14 can be assembled with the electricalcircuit 11 during the second molding shot at 114 instead of the firstmolding shot at 110. In another example, if the electrical circuit 11does not include any embedded conductors, such as the embodiments ofFIGS. 6 and 7, the first molding shot at 110 can be used to form thepolymeric substrate 16 for supporting conductors that are either setdown or printed onto the polymeric substrate 16.

II. Operation

In use, the illumination assembly 10 can be coupled with a suitablepower source through the connector portion 32 to supply electricalcurrent to the electrical circuit 11. Electrical current can flowthrough the embedded conductors 12 a-b and the printed conductors 18 a-dto provide power to the various electrical components 24-26, includingthe LED 22. Thermal energy generated by the LED 22 during operation ofthe LED 22 can be dissipated through the heat spreader 14, eitherdirectly, or through the polymeric substrate 16.

The illumination assembly 10 can provide a multi-layer assembly whichlayers a heat spreader, a non-conductive polymeric material, electricalconductors, and an LED to facilitate thermal energy management. Improvedheat management can facilitate forming illumination assemblies havingmore advanced electronic functionality and higher power levels that donot overheat during use. Generally, an LED is considered high power ifit operates at 350 mA or more and consumes greater than 1 watt. Forexample, improved heat management can allow for the use of thinnerpolymeric layers forming the polymeric substrate 16 and the firstpolymeric layer 28 while still enabling advanced circuit functions andhigh power LEDs without overheating. Decreasing thickness of thepolymeric substrate 16 and/or the first polymeric layer 28 can save onmaterial costs and increase flexibility in satisfying the desired formfactor of the lighting assembly 10 based on its intended end use.

In addition, the first polymeric layer 28 can provide a mechanical sealfor holding elements of the lighting assembly 10 in place and optionallyprovide a moisture seal to protect the electronics from moisture damage.The materials for the polymeric substrate 16 and the first polymericlayer 28 can be selected such that the first polymeric layer 28 isbonded to the exposed surfaces of the polymeric substrate 16 during themolding process. The bonded first polymeric layer 28 can facilitatesecuring the LED 22 and other electrical components 24, 26 in place,which can decrease the likelihood of these components becoming dislodgedand losing their connection to the electrical circuit 11 and/or the heatspreader 14. The bonded first polymeric layer 28 may also facilitatesecuring the connection between the printed conductors 18 and theembedded conductors 12. The bonded first polymeric layer 28 can alsoinhibit moisture from infiltrating the circuit and potentiallyelectrically shorting the connection between the electrical components22-26 and the conductors 12, 18 and between the printed and embeddedconductors 12 and 18.

III. Additional Embodiments

FIG. 5 illustrates an example of a lighting assembly 210 that is similarto the lighting assembly 10 except for the configuration of theelectrical circuit. Therefore, elements of the lighting assembly 210similar to those of the lighting assembly 10 are labeled with the prefix200.

The illumination assembly 210 is shown without the first polymeric layer228 for clarity. The polymeric substrate 216 extends in multipledimensions and includes a connector portion 232 for connecting theillumination assembly 210 to a suitable power source. The electricalcircuit 211 includes a combination of multiple conductors 212 a-fembedded within the polymeric substrate 216 and multiple printedconductors 218 a-d printed onto the interior surface 220 of thepolymeric substrate 216. The printed conductors 218 a-d can be connectedto one or more embedded conductors, such as embedded conductors 212 a-b,to provide current flow to the printed conductors 218 a-d.

The electrical circuit 211 also includes multiple electrical components222-226 connected to the embedded conductors 212 a-f or the printedconductors 218 a-d. For example, LEDs 222 a-b can be connected toembedded conductors 212 c-d and 212 e-f and an additional LED 222 c canbe connected to printed conductors 218 c-d. A heat spreader (not shown)can be thermally coupled to one or more of these LEDs 222 a-c as neededin a manner similar to that discussed above with respect to FIGS. 2 and3. Additional electrical components, such as electrical components 224and 226 can be connected to other printed conductors or embeddedconductors based on the design of the circuit.

The embedded and printed conductors 212 and 218, respectively, extendacross multiple planes of the multi-planar polymeric substrate 216 andthus the illumination assembly 210 can emit light in multiple directionsby providing the LEDs 222 in different planes. The printed conductors218 can be printed with narrower widths and higher densities than theembedded conductors 212 and thus facilitate increasing the complexity ofthe circuit by increasing connector densities and/or decreasing the sizeof the circuit needed to support the desired electrical components. Thelarger embedded conductors 212 can be used as needed based on the powerrequirements of the electrical components connected to the embeddedconductors 212. The printed conductors 218 are typically more expensivethan the embedded conductors 212 and thus the embedded conductors 212can be used where feasible to decrease costs compared to a circuit madepredominately of printed conductors.

FIG. 6 illustrates an example of a lighting assembly 310 that is similarto the lighting assembly 10 except for the configuration of theelectrical circuit and the polymeric substrate. Therefore, elements ofthe lighting assembly 310 similar to those of the lighting assembly 10are labeled with the prefix 300. FIG. 6 illustrates a portion of thelighting assembly 310 that includes a single LED; however, the lightingassembly 310 can be part of a more complex lighting assembly thatincludes a larger electrical circuit and multiple components, such asthat shown in FIG. 1 or FIG. 5, for example.

In the lighting assembly 310, the polymeric substrate 316 can be in theform of a film or a layer of molded polymeric material that is thermallyconductive and electrically insulating. Generally, the thinner thepolymeric substrate 316, the more efficient the heat transfer is to theadjacent heat spreader 314. Additional factors, such as the form factorof the device in which the lighting assembly 310 is to be used and/ormanufacturing limitations may also effect the thickness of the polymericsubstrate 316.

The conductors 312 a-b can be printed onto the polymeric substrate 316in a manner similar to that described above with respect to the printedconductors 18 of the illumination assembly 10. Alternatively, theconductors 312 a-b can be non-printed conductors that are supported bythe polymeric substrate 316 by lying on the interior surface 320 orbeing at least partially embedded within the polymeric substrate 316.For example, the conductors 312 a-b can be formed using a metal web asdescribed above for the method 100 of FIG. 4. In this scenario, thesupported conductors 312 a-b can be partially embedded within thepolymeric substrate 316 or be supported by the interior surface 320 suchthat the conductors 312 a-b are predominately disposed on the interiorside of the polymeric substrate 316.

The LED 322 can be electrically coupled to the conductors 312 a-b in amanner similar to that described above with respect to the illuminationassembly 10 of FIG. 1, such as through soldering or a conductive epoxy.The heat spreader 314 can be disposed adjacent the LED 322 fordissipating heat generated by the LED. In the embodiment of FIG. 6, theheat spreader 314 is not in direct contact with the LED 322 and islocated entirely exteriorly of the interior surface 320 of the polymericsubstrate 316. Heat generated by the LED 322 is transferred through theconductors 312 a-b, through the polymeric substrate 316, and to the heatspreader 314.

The first polymeric layer 328 can be molded around the LED 322, theconductors 312 a-b, the polymeric substrate 316, and the heat spreader314 to secure these elements of the lighting assembly 310 togetherwithout the use of mechanical fasteners. The molded first polymericlayer 328 can also provide a moisture seal to inhibit moisture frominterfering with the electrical connections between the LED 322 and theconductors 312 a-b. The first polymeric layer 328 can be molded aroundonly a portion of the heat spreader 314, as illustrated, such thatportions of the heat spreader 314 can be exposed to atmosphere or anadjacent component in the end use device to facilitate heat dissipation.However, the first polymeric layer 328 could optionally be molded aroundthe entire heat spreader 314. The first polymer layer 328 can be moldedat least partially around the heat spreader 314 such that the firstpolymer layer 328 secures the heat spreader 314 in place and/or anadhesive can be used to secure the heat spreader 314 in place relativeto the LED 322.

The lighting assembly 310 can be part of a more complex andmulti-dimensional circuit that includes multiple electrical components.Individual heat spreaders 314 can be provided adjacent each LED or otherelectrical component, as needed, to dissipate heat, including componentspositioned in different planes. This allows for the location and/or thesize of the heat spreader to be customized for each LED or otherelectrical component and facilitates forming lighting assemblies thatsatisfy more complex form factors.

The lighting assembly 310 can be part of a multi-component andmulti-dimensional assembly, similar to those illustrated in FIGS. 1 and4. The lighting assembly 310 can be used with an electrical circuit thatincludes conductors supported by the polymeric substrate 316 in the samemanner as the conductors 312 a-b or a combination of different types ofconductors, including embedded and/or printed conductors.

For example, FIG. 7 illustrates a lighting assembly 410 similar to thatof the lighting assembly 310 except for differences in the electricalcircuit and the first polymeric layer. Elements of the lighting assembly410 similar to those of the lighting assembly 310 are labeled with theprefix 400.

As illustrated in FIG. 7, the electrical circuit 411 can includeconductors 412 a-b supported on the interior surface 420 of thepolymeric substrate 416 as well as printed conductors 418 a-b that areprinted onto the interior surface 420. The LED 422 can be electricallyconnected to the conductors 412 a-b and thermally coupled to the heatspreader 422. An additional electrical component 424 can be connected tothe printed conductors 418 a-b.

The polymeric substrate 416 can be in the form of a film or a layer ofmolded polymeric material having a desired thickness. The firstpolymeric layer 418 can be molded around the LED 422, the conductors 412a-b, the conductors 418 a-b, the polymeric substrate 416, and the heatspreader 414 to secure these elements of the lighting assembly 410together without the use of mechanical fasteners and to optionallyprovide a moisture seal to inhibit moisture from interfering with theelectrical connections in the circuit 411.

The size and the location of the heat spreader 414 can be configured toaccommodate only the LED 422 rather than both the LED 422 and theelectrical component 424. Customizing the size and the location of theheat spreader 414 based on the heat dissipation needs of the circuit candecrease the parts and materials used in the lighting assembly 411 andfacilitate designing lighting assemblies that are multi-dimensional.

FIG. 8 illustrates another example of a lighting assembly 510 that issimilar to the lighting assemblies 310 and 410 except for differences inthe electrical circuit, the heat spreader, and the first polymericlayer. Elements of the lighting assembly 510 similar to those of thelighting assembly 310 and 410 are labeled with the prefix 500.

In the example of FIG. 8, the lighting assembly 510 includes embeddedconductors 512 a-b, printed conductors 518 a-b, an LED 522 electricallycoupled to the embedded conductors 512 a-b, and an additional electricalcomponent 524 electrically coupled to the printed conductors 518 a-b.The first polymeric layer 528 can be molded around the LED 522, theconductors 512 a-b, the polymeric substrate 516, the electricalcomponent 524, and the printed conductors 518 a-b to secure theseelements together and optionally inhibit moisture from contacting thecircuit.

The heat spreader 514 in this example is a separate component that isnot coupled with the other components of the assembly 510 by theover-molded first polymeric layer 528. The heat spreader 514 can besecured adjacent the exterior surface 564 of the polymeric substrate 516using an adhesive or mechanical fasteners. In one example, the heatspreader 514 can be part of the end use device to which the lightingassembly 510 is intended for use and coupling the lighting assembly 510with the end use device also couples the heat spreader 514 to thelighting assembly 510. For example, the heat spreader 514 could be athermally conductive part of a lamp which is intended for use with thelighting assembly 510. This configuration can provide a heat spreaderhaving a large surface to facilitate heat dissipation and can alsosimplify manufacturing of the lighting assembly 510. It is also withinthe scope of the invention for the first polymeric layer 528 to beover-molded around the heat spreader 514 to secure the heat spreader 514in place in a manner similar to that described above for the lightingassembly 310 and 410.

FIG. 9 illustrates another example of a lighting assembly 610 that issimilar to the lighting assembly 10 except for differences in theelectrical circuit, the heat spreader, and the first polymeric layer.Elements of the lighting assembly 610 similar to those of the lightingassembly 10 are labeled with the prefix 600. FIG. 9 illustrates aportion of the lighting assembly 610 that includes a single LED;however, the lighting assembly 610 can be part of a more complexlighting assembly that includes a larger electrical circuit and multiplecomponents, such as that shown in FIG. 1 or FIG. 5, for example.

The lighting assembly 610 includes a polymeric substrate 616 in the formof a thin film or sheet of polymeric material. Multiple conductors 618a-c can be printed onto the interior surface 620 of the polymericsubstrate 616 for supplying electrical current to the LED 622. Thepolymeric substrate 616 can include an aperture 668 adjacent the LED 622through which a thermal management device 670 extends to thermallycouple the LED 622 with the heat spreader 614 disposed on the exteriorside 664 of the polymeric substrate 616. The thermal management device670 can be a separate component or can be integrally formed with theheat spreader 614. For example, the heat spreader 614 can be a moldedaluminum or copper heat sink that includes a raised portion forming thethermal management device 670 that is configured to extend through theaperture 668 to thermally couple the LED 622 with the heat spreader 614.

The polymeric substrate 616 can be made of a non-conductive materialaccording to any known film-forming process. The polymeric substrate 616can be pre-formed, with or without the aperture 668, or formed in-linewith one or more components of the lighting assembly 610. For example,the conductors 618 a-c can be printed onto the pre-formed polymericsubstrate 616, the thermal management device 670 and the heat spreader614 can be assembled with the polymeric substrate, and the LED 622 canbe electrically coupled to the conductors 618 a-c. In another example,the polymeric substrate 616 can be formed around the assembled thermalmanagement device 670 and heat spreader 614.

FIG. 10 illustrates another example of a lighting assembly 710 that issimilar to the lighting assembly 310 of FIG. 6 except for differences inthe heat spreader, the polymeric substrate, and the first polymericlayer. Elements of the lighting assembly 710 similar to those of thelighting assembly 310 are labeled with the prefix 700. FIG. 10illustrates a portion of the lighting assembly 710 that includes asingle LED; however, the lighting assembly 710 can be part of a morecomplex lighting assembly that includes a larger electrical circuit andmultiple components, such as that shown in FIG. 1 or FIG. 5, forexample.

The lighting assembly 710 of FIG. 10 includes a thermal interface layer780 thermally coupling the heat spreader 714 and the LED 722 that is nota molded polymeric substrate material. The thermal interface layer canbe a thermal interface material (TIM) that is thermally conductive, butelectrically insulating. Non-limiting examples of suitable thermalinterface materials include copper, aluminum, or ceramic impregnatedepoxies or silicones, graphine, carbon nanotubes, nano-glue, ceramiccoated copper, ceramic coated aluminum, and oxidized aluminum. Thethermal interface layer 780 can be applied at least to an interiorsurface of the heat spreader 714 adjacent the LED 722 in the assembledlighting assembly 710 and can be a separate layer or a layer that isintegrally formed with the heat spreader 714. In one example, thethermal interface layer 780 can be formed by oxidizing the interiorsurface of an aluminum heat spreader 714.

In the embodiment of FIG. 10, the first polymeric layer 728 and/or theheat spreader 714 can provide the support structure for the electricalcircuit 711 in the absence of a separate polymeric substrate layer (suchas the polymeric substrate 316 of FIG. 6). The first polymeric layer 728can function as both the over-molded polymeric layer that provides amechanical seal for holding elements of the lighting assembly 710together as well as provide a substrate for supporting elements of theelectrical circuit 711. The heat spreader 714 can optionally provideadditional structural support to one or more components of theelectrical circuit 711. In this manner, the lighting assembly 710 can beformed from a single-shot molding process, rather than a multiple-shotmolding process.

In yet another example, the lighting assembly can include both a thermalinterface layer and a polymeric substrate layer. FIG. 11 illustratesanother example of a lighting assembly 810 that is similar to thelighting assembly 410 of FIG. 7 and 710 of FIG. 10 except fordifferences in the electrical circuit, heat spreader, thermal interfacelayer, and the first polymeric layer. Elements of the lighting assembly810 similar to those of the lighting assemblies 410 and 710 are labeledwith the prefix 800. FIG. 11 illustrates a portion of the lightingassembly 810 that includes a single LED; however, the lighting assembly810 can be part of a more complex lighting assembly that includes alarger electrical circuit and multiple components, such as that shown inFIG. 1 or FIG. 5, for example.

In the embodiment of FIG. 11, the polymeric substrate 816 can include anopening 882 adjacent the heat spreader 814 and the LED 822 in theassembled lighting assembly 810. The thermal interface layer 880 can beprovided within the opening 882 to thermally couple the LED 822 and theheat spreader 814. In this example, the polymeric substrate 816 canprovide structural support for the electrical circuit 811 in a mannersimilar to that described above for previous embodiments while thethermal interface layer 880 facilitates heat transfer between the LED822 and the heat spreader 814.

It will be understood that it is within the scope of the invention thatany of the lighting assemblies 10, 210, 310, 410, and 510 describedherein can be made in a single-shot molding process without a separatepolymeric substrate and including a thermal interface layer forthermally coupling the heat spreader and the electrical component in amanner similar to that described above for the lighting assembly 710 ofFIG. 10. In addition, it will also be understood that it is within thescope of the invention that any of the lighting assemblies 10, 210, 310,410, and 510 described herein can include a polymeric substrate madeaccording to a multiple-shot molding process, in addition to a thermalinterface layer for thermally coupling the heat spreader and theelectrical component in a manner similar to that described above for thelighting assembly 810 of FIG. 11.

In addition, while the embodiments of the lighting assemblies 10, 210,310, 410, 510, 610, 710, and 810 are primarily described in the contextof thermally coupling a heat spreader with an LED, it will be understoodthat a heat spreader can be coupled with any exemplary electricalcomponent other than an LED in a similar manner without deviating fromthe scope of the invention.

IV. Conclusion

The lighting assemblies described herein can address several challengesrelated to solid-state lighting applications using LEDs. For example,the lighting assemblies described herein integrate the electricalcircuit with a polymeric substrate that can be formed or molded into adesired three-dimensional shape. The heat spreader can also beintegrated into the lighting assembly by embedding the heat spreaderwithin the polymeric substrate and/or molding the first polymeric layeraround the heat spreader. Integration of the electrical circuit and/orthe heat spreader can also decrease labor and manufacturing costscompared to designs which utilize multiple separate components andsub-components. In addition, integrating the electrical circuit and/orthe heat spreader into the polymeric substrate or the first polymericlayer that can be formed or molded into complex and three-dimensionalshapes increases the ability to satisfy end use applications requiringcomplex form factors.

The ability to place LEDs in different planes can be used to aim lightin a desired direction, which can increase efficiency of the end usedevice. For example, a ceiling light that produces an isotropicradiation pattern of light tends to create a hot spot of light directlybelow it. The light bulb in the ceiling light can be replaced with thelighting assembly as described herein which includes multiple LEDs aimedso as to generate a non-isotropic radiation pattern that can create amore uniform distribution of light across the floor. The more uniformlydistributed light may appear brighter to the viewer, even if the totallight output from the ceiling light is the same. The ability to controllight patterns could be leveraged to produce lighting products that meetperformance specifications while requiring less light, and thus lesspower.

A traditional lighting assembly typically includes a printed circuitboard and would require multiple boards and circuit jumpers in order toachieve multi-directional lighting where the electronics conform to theform factor of the end use device. Such a device would be limited interms of the size and complexity of the multi-dimensional shape of thelighting assembly. Printed conductors can be used in order to achieve acircuit that can better conform to the contour of the end use device.However, printed conductors can only deliver a small amount ofelectrical power and dissipate a small amount of heat energy and thus aconstruction that includes only printed conductors is generally not ableto sustain the power levels necessary for achieving general lightingfunctionality. Providing the circuit with a sheet metal onlyconstruction can improve the form factor and power handling capacitycompared to a device that uses only printed conductors; however thetraces are generally too big to support the electronics necessary toachieve the advanced electronic functionality required in more complexlighting designs.

The lighting assemblies described herein utilize conductors supported bythe polymeric substrate in a combination of different ways, such asprinting and embedding, in order to provide a circuit that satisfies theelectrical current needs of the components as well as component densityneeds. The combination of more traditional types of conductors withprinted conductors can save on materials costs by only utilizing theprinted conductors where needed.

The number, size, and location of the heat spreaders can also becustomized based on the design of the lighting assembly. Utilizing heatspreaders only where needed can save on materials and manufacturingcosts, as well as facilitate satisfying complex three-dimensional formfactor requirements. The use of heat spreaders with the polymericsubstrate and the supported conductors can improve heat management ofthe assembly, thus allowing more complex and higher current lightingdesigns.

The above description is that of current embodiments of the invention.Various alterations and changes can be made without departing from thespirit and broader aspects of the invention as defined in the appendedclaims, which are to be interpreted in accordance with the principles ofpatent law including the doctrine of equivalents. To the extent notalready described, the different features and structures of the variousembodiments of the illumination assemblies 10, 210, 310, 410, 510, 610,710, and 810 may be used in combination with each other as desired. Thatone feature may not be illustrated in all of the embodiments is notmeant to be construed that it cannot be, but is done for brevity ofdescription. Thus, the various features of the different embodiments ofthe illumination assemblies 10, 210, 310, 410, 510, 610, 710, and 810may be mixed and matched as desired to form new embodiments, whether ornot the new embodiments are expressly disclosed.

This disclosure should not be interpreted as an exhaustive descriptionof all embodiments of the invention or to limit the scope of the claimsto the specific elements illustrated or described in connection withthese embodiments. For example, and without limitation, any individualelement of the described invention may be replaced by one or morealternative elements that provide substantially similar functionality orotherwise provide adequate operation. This includes, for example,presently known alternative elements, such as those that might becurrently known to one skilled in the art, and alternative elements thatmay be developed in the future, such as those that one skilled in theart might, upon development, recognize as an alternative.

The invention is not limited to the details of operation or to thedetails of construction and the arrangement of the components set forthin the above description or illustrated in the drawings. The inventionmay be implemented in various other embodiments and practiced or carriedout in alternative ways not expressly disclosed herein.

The phraseology and terminology used herein are for the purpose ofdescription and should not be regarded as limiting. The use of“including” and “comprising” and variations thereof is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items and equivalents thereof. Further, enumeration may beused in the description of various embodiments. Unless otherwiseexpressly stated, the use of enumeration should not be construed aslimiting the invention to any specific order or number of components.Nor should the use of enumeration be construed as excluding from thescope of the invention any additional steps or components that might becombined with or into the enumerated steps or components.

The disclosed embodiment includes a plurality of features that aredescribed in concert and that might cooperatively provide a collectionof benefits. The present invention is not limited to only thoseembodiments that include all of these features or that provide all ofthe stated benefits.

Any reference to claim elements in the singular, for example, using thearticles “a,” “an,” “the” or “said,” is not to be construed as limitingthe element to the singular.

Directional terms, such as “front,” “back,” “vertical,” “horizontal,”“top,” “bottom,” “upper,” “lower,” “inner,” “inwardly,” “outer” and“outwardly,” are used to assist in describing the invention based on theorientation of the embodiments shown in the illustrations. The use ofdirectional terms should not be interpreted to limit the invention toany specific orientation.

1. An illumination assembly comprising: a polymeric substrate; anelectrical circuit including two conductors supported by the polymericsubstrate; a light source electrically coupled to the two conductors; aheat spreader thermally coupled to the LED light source; and a firstpolymeric layer comprising a thermoplastic material over-molded aroundat least portions of the polymeric substrate, the two conductors, thelight source, and the heat spreader.
 2. The illumination assembly ofclaim 1 wherein the polymeric substrate defines an aperture and whereinthe heat spreader is thermally coupled to the light source through theaperture.
 3. (canceled)
 4. The illumination assembly of claim 1 whereinthe light source is not in direct contact with the heat spreader.
 5. Theillumination assembly of claim 1 comprising a thermally conductive andelectrically insulating material between the light source and the heatspreader.
 6. The illumination assembly of claim 1 wherein the twoconductors are one of printed on the first polymeric substrate and atleast partially embedded within the first polymeric substrate.
 7. Anillumination assembly comprising: a polymeric substrate; an electricalcircuit including: a first pair of conductors at least partiallyembedded within the polymeric substrate; and a second pair of conductorsprinted on the polymeric substrate; a light source electrically coupledto the electrical circuit; a heat spreader thermally coupled to thelight source; and a first polymeric layer over-molded around at leastportions of the polymeric substrate, the electrical circuit, the lightssource, and the heat spreader.
 8. The illumination assembly of claim 7wherein the second pair of conductors is electrically coupled to thefirst pair of conductors.
 9. The illumination assembly of claim 7wherein the light source is not in direct contact with the heatspreader.
 10. The illumination assembly of claim 9 comprising athermally conductive and electrically insulating material between thelight source and the heat spreader.
 11. (canceled)
 12. The illuminationassembly of claim 7 wherein the first polymeric layer forms at least oneof a mechanical seal and a moisture seal around the light source, thefirst pair of conductors, and the second pair of conductors. 13.(canceled)
 14. The illumination assembly of claim 7 wherein a firstportion of the electrical circuit is disposed in a first plane, and asecond portion of the electrical circuit is disposed in a second plane,different than the first plane.
 15. The illumination assembly of claim 7wherein the light source is electrically coupled to the first pair ofconductors.
 16. A method of forming an illumination assembly comprising:forming a polymeric substrate having opposing first and second sides;forming an electrical circuit including two conductors supported on thefirst side of the polymeric substrate; electrically coupling a lightsource with the two conductors; thermally coupling a heat spreader withthe light source, the heat spreader at least primarily disposed on thesecond side of the polymeric substrate; and over-molding a firstpolymeric layer over at least portions of the light source, the twoconductors, the polymeric substrate, and the heat spreader. 17.(canceled)
 18. The method of claim 16 wherein the over-molding of thefirst polymeric layer forms at least one of a mechanical seal and amoisture seal between the light source, the two conductors, and thepolymeric substrate.
 19. The method of claim 16 wherein the heatspreader is entirely on the second side of the polymeric substrate, andthe light source is not in direct contact with the heat spreader. 20.The method of claim 16 wherein the forming an electrical circuitcomprises printing the two conductors onto the first side of thepolymeric substrate.